An underground storage tank system includes an underground storage tank as well as underground pipes and adapters connected thereto. An underground storage tanks is defined as of which 10% or more of the total volume is buried underground, and such storage tank is used for storing oils, solvents, fuels, etc. In Taiwan, a majority of gas stations applies underground storage tanks to store gasoline and diesel fuel for sale, and fuels in gas stations are pumped via underground pipes from storage tanks to fuel dispensers. At present, about 90% of the storage tanks are made of steels, and about 60% of the underground pipes and adapters are made of metals in Taiwan. The gasoline and diesel fuel stored in the underground storage tanks in the gas stations are classified as contaminating materials according to the announcement by Environmental Protection Administration (EPA) in Taiwan. If the corrosion resistance treatment for the underground storage tank systems made of metals is poor, environmental pollution caused by the leakage of oils from corroded tanks may occur.
Current pollution control requires leakage detections of underground storage tank systems. The leakage detections include tightness test of tanks and pipes, inspection of organic vapor or floating oil in monitoring wells, and/or examination of soil contamination level by analysis instruments. As an abnormality is detected, the fuel has already leaked out of the underground storage tank system, and the leakage may have lasted for a certain period of time as detected, resulting serious pollution to the environment. To remedy leakage of petroleum products is a complicated process, which may include soil remediation and underwater remediation, of which the cost is huge, and more importantly, the damage to the environment is severe. Since gasoline and diesel duel contain a number of materials hazardous to human, once the gasoline or diesel fuel leakage occurs, the damaged caused is beyond estimation. However, the current leakage detection techniques of underground storage tank system either can only be done after gasoline or diesel has leaked or requires operating personnel getting into the tanks, which techniques are time-consuming, dangerous, and expensive.
Therefore, researchers have been working on developing new corrosion detection techniques to overcome the deficiencies of the current techniques.
A prior art disclosed a detection system for underground storage tank systems, incorporating a robot travelling the interior of a tank for performing the detection. However, the size of the robot restricts it from getting into underground pipes of the underground storage tank systems, therefore, only the corrosion information of the tank is provided. Hence, the corrosions of the pipes and adapters of the systems can not be detected according to the method. In addition, while the detection of a storage tank system is taking place, fuels cannot be provided by the storage tank system.
Another prior art disclosed an inspection apparatus for detecting defects, such as cracks, of pipes, which primarily utilizes optical fibers cooperating with image oscilloscopes and monitors, wherein the optical fiber image oscilloscopes extend into pipes to record images for detecting defects. However, the length of the optical fiber is limited, and the pipes may have corners which cannot be reached by the optical fiber; thus, the inspection apparatus cannot cover all sections of the pipes. In addition, the apparatus is merely for inspecting pipes, fuels cannot be provided from the pipes while the detection is taking place, and the inspecting process is time-consuming.